Azithromycin

C. diff Risk

Medium

Oral Bioavailability

Excellent

Approximate Cost

IV-$9/d PO-$1/d

Spectrum Of Activity

Dosing

500 mg/dose PO x 1 dose on Day 1
then 250 mg/dose PO q24h on Days 2-5

500 mg/dose IV q24h for 2 days then switch to oral therapy

Dose adjustment not necessary.

Use with caution if CrCl<10mL/minute.

General Information

Common Usage

Community acquired pneumonia, Pertussis, upper respiratory tract infections, Chlamydial infections, mycobacterial infections

Drug Monitoring

Monitor QTc in patients with increased risk.

Adverse Effects

Prolongation of QTc interval.

One study suggested that there is 3-8 fold risk of pyloric stenosis with use of azithromycin in neonates. Therefore clinicians need to weigh benefits and risks when considering whether to use azithromycin in young infants.

Major Interactions

While less risk of interaction compared to other macrolides, several potential CYP450 interactions may occur; consult a pharmacist for for more details.

Avoid concurrent use with other drugs that prolong QTc

Oral Liquids

Concentration: 40 mg/mL
Taste: bitter
Not all strengths of oral liquids are listed nor are available on IWK formulary

Tablet/Capsule Strengths

250 mg tablet
Tablets and capsules are preferred especially over an unpleasant tasting liquid.
Not all strengths of oral tablets/capsules are listed and they are not all available on the IWK formulary.

Pharmacology

Antimicrobial class: Macrolide

Average serum half life: Pediatrics: 54.5 hours

Route of Elimination: 50% excreted unchanged in bile.

6-14% excreted unchanged in urine.